Once upon a time, an emissary from England journeyed to the peoples of the East on a mission of peace. With him he carried his totemic deity, a bear.The time was 2010, the man was the artist Grayson Perry and he traveled to Germany on a combined motorcycle and shrine (for the god) entitled the “AM1.” It can be seen at the entrance to Perry’s new exhibition, “The Tomb of the Unknown Craftsman,” which opens tomorrow at the British Museum in London.The bear, a teddy named Alan Measles that has been worshipped by Perry since the early 1960s, is too precious to exhibit and is replaced by a replica. The journey, as Perry, born in 1960, explains in the catalog, was undertaken because in his childhood “the Germans were the default enemy, and so they became a metaphor for all that was bad in my experience. Alan and I needed to make peace with our old imagined adversary.”If you think that’s unbearably twee, then the show isn’t for you. Those prepared to suspend disbelief and briefly enter Perry’s fantasy world, will have eye-opening fun. He is, of course, well known for being both a transvestite and a contemporary artist many of whose works take the form of decorated pottery.Some might say he is an extremely English phenomenon. I remember on the night he won the Turner Prize in 2003, a fellow guest at the award dinner -- who happened to be German -- leaned across the table and whispered, “Only in Britain.” Perry, dressed as his female alter ego Claire, was taking a photo call along with his wife and daughter.In fact, there is a Teutonic aspect to him. You could say Perry is a unique amalgam of bear-loving Christopher Robin, Eddie Izzard and Joseph Beuys (1921-1986) of Germany, who came up with the notion of the artist as a latter-day shaman, injecting magic and mysterious ritual into modern life.Although there are some bears and a bear shrine on view, and one female costume -- the “High Priestess Cape” (2007) -- it’s the third side that’s most evident: the artist as myth maker and medicine man.This is that usually horrible thing, an “intervention” -- a contemporary artist doing something, usually embarrassing, in a museum. This one, perhaps because it was Perry’s idea not the museum’s, is the exception. It works.The exhibits are a mixture of items from the collection and works by Perry. Unexpectedly, they enhance each other. The museum pieces, some of them thousands of years old, look edgy and contemporary; Perry’s own stuff looks timeworn and in context. In other words, he does what artists often try to do: He invents an artistic ancestry for himself.His choice from the museum’s collection is highly personal. There’s nothing grand and little classical, these are mainly humble and vernacular objects, many from Africa and Japan, all the product of anonymous men and women, some rough, some beautiful, a few highly sexual (a Perry touch).He exhibits some of his own signature pots, and also a large tapestry and several sculptures, including the centerpiece, an iron boat festooned with casts of works from the museum. Like the other Perry pieces, it looks antique and is brand new.At first glance, it’s often hard to tell whether you are looking at a Grayson Perry or an artifact from an ancient civilization. That’s a good sign. The show is one mammoth work by Perry, and the most interesting he has created to date.